The present invention relates to key telephone systems and more particularly to a key telephone system which is programmable at the site of installation to implement different features.
Key telephone systems generally comprise a plurality of telephones (also referred to as "telephone stations") and a central key service unit ("KSU") which interconnects the telephones with each other and to outside telephone trunk lines. The KSU provides control functions for the key telephone system and establishes communication paths between telephone stations. When outside calls are involved, the KSU establishes communication paths between telephone stations and telephone trunk lines.
Depending upon their sophistication and complexity, key telephone systems can provide a wide variety of system features. Examples of such features include the designation of which telephone(s) in the system can originate and terminate pages; provision for night transfer service including station service and automatic answering device service; message waiting indication; designation of call pick-up groups, call distribution groups, and group answering; central office ring assignments; telephone station outgoing call restrictions; provision of private lines to certain telephone stations; soft page groups; barge in capability; amplification for hard of hearing users; call waiting tones; timers for flash key, central office release, hold recall, and camp-on; automatic central office line selection; auto ringing line selection; central office line call back waiting time selection; and others.
In the past, installation of such features has generally been made at the time of manufacture of the key telephone system. Some key telephone systems provide for programming such features during system installation at the user's premises. In such cases, however, it has been necessary for the system installer to use a special terminal at the time of installation to program desired features into the key telephone system. The use of such separate installation terminals is both expensive and often impractical.
It would be advantageous to provide a key telephone system which can be programmed or re-programmed at any time, at the user's premises, without the need for special equipment. The programming of such a system should be straightforward and easy to accomplish without extensive training. It would be further advantageous to provide a key telephone system wherein re-programming of system features can be accomplished while the system is in use, without affecting the normal operation of the system during the re-programming activity.
The present invention provides to such a key telephone system.